Summary Description and Specific Aims This research aims at understanding and predicting the utilization or nonutilization of medical, specialty mental health, and other services for mental health, alcoholism, and drug abuse problems. Phase I of the research involves description and comparison of the proportions of a state's population needing, seeking, and utilizing services, based on the results of a now-completed large survey (N=4,777) of the Colorado population. Using those data, the proportion of the population that is "in need of services" will be determined using five different criteria of need: 1. Having a current psychiatric diagnosis as determined from the NIMH Diagnostic Interview Schedule; 2. Presence of numerous psychiatric symptoms; 3. Current impairments in one's life caused by symptoms; 4. Low scores in various areas of daily functioning; and 5. High scores on a depression "screening" or "demoralization" scale. Proportions of persons from the total population and key demographic subgroups either seeking or receiving services from different types of caregivers (medical, specialty mental health, and other) will also be estimated. Demographic subgroups studied will include males and females, ethnic minorities (Hispanic, black, and Native American), persons in poverty, the unemployed persons, the elderly, rural and urban dwellers, and military veterans. Phase II of the research will determine quantitatively, at both the individual and subarea levels, the effects of a number of variables upon the probability that a person will seek and obtain help from formal caregivers. The variables will include need for services, demographic characteristics, acquired social statuses, socio-ecological characteristics, and environmental availability and physical accessibility of services. Procedures for direct applying the results to services estimation and planning will be sought.